Alkyl-n-alkyl-chlorophenoxythioacetimidates as selective herbicides

ABSTRACT

Alkyl-N-alkyl-chlorophenoxythioacetimidates are prepared by reacting N-alkyl-di- or trichlorophenoxythioacetamide with alkyl iodide in the presence of sodium alcholate. The compounds are useful as herbicides.

United States Patent [451 Mar. 7, 1972 Rumanowski [54]ALKYL-N-ALKYL-CHLOROPHENOX- YTHIOACETIMIDATES AS SELECTIVE HERBICIDES[72] Inventor: Edmund J. Rumanowski, Dover, [73] Assignee: AlliedChemical Corporation, New York,

[22] Filed: July 3, 1969 21 App1.No.: 839,078

[52] 11.8. C1. ..71/98, 260/453 R [51] Int. Cl. ..A0ln 9/12 [58] Fieldof Search ..260/453 R; 71/98 [56] References Cited UNITED STATES PATENTS2,412,510 12/1946 Jones ..71/98 2,811,526 10/1957 Burtnen. ...260/453 R3,394,181 7/1968 Bell ..424/327 3,424,723 1/1969 Yates et a1. ..71/983,488,355 H1970 Levy ..260/453 R FOREIGN PATENTS OR APPLICATIONS1,207,146 12/1965 Germany ..71/98 OTHER PUBLICATIONS Johnston, TheRelationship of Structure to Activity in Plant Growth-RegulatingCompounds." (1961 CA 55 p. 24,622

Primary Examiner-Elbert L. Roberts Assistant Examiner-G. HollrahAttorney-Patrick L. Henry and Fred L. Kelly [57] ABSTRACTAlkyl-N-alkyl-chlorophenoxythioacetimidates are prepared by reactingN-alkyl-dior trichlorophenoxythioacetamide with alkyl iodide in thepresence of sodium alcholate. The compounds are useful as herbicides.

6 Claims, No Drawings ALKYL-N-ALKYL- CIILOROPHENOXYTI-IIOACETIMIDATES ASSELECTIVE HERBICIDES BACKGROUND OF THE INVENTION This invention relatesto novel chlorophenoxythioacetimidates; in particular, it relates toalkyl-N-alkylchlorophenoxythioacetimidates, their preparation and use asherbicides.

The need to control undesirable plant growth for efficient cultivationof crops has given rise to the development of a great variety ofherbicidal agents. However, many of the chemical herbicides availableheretofore do not have adequate potency or selectivity to afford optimumresults. An effective herbicide must be highly effective againstundesirable plants while remaining harmless with respect to the plantbeing cultivated, such as corn and wheat.

SUMMARY OF THE INVENTION The novel compounds of the instant inventionare diand trichlorophenoxythioacetimidates of the formula:

wherein R is hydrogen or chlorine, and R and R" are lower alkyls havingone to four carbon atoms.

These compounds are prepared by reacting N-alkyl-diortrichlorophenoxythioacetamide with alkyl iodide in the presence of asodium alcoholate to form the corresponding alkyl-N-alkyl-diortrichlorophenoxythioacetimidates. The novel compounds are useful asherbicides.

DETAILED DESCRIPTION OF THE INVENTION Preparation of the instantcompounds is accomplished by reacting a lower alkyl iodide with theappropriate N-alkylchlorophenoxythioacetamide in the presence of anequivalent amount of sodium alcoholate, for example, according to thefollowing sequence:

R V V Approximately equimolar amounts of the two substrates may be used,although an excess of either might be used to achieve a higher yieldwith respect to the other.

The reaction may be conducted in an inert solvent; it is convenient touse an alcohol which is a byproduct of the synthesis. Preferably, thereaction will be conducted at a temperature within the range of 3570 C.,and more preferably, 40-45 C. Reaction times as short as about one-halfhour or less have been found to be adequate, although longer reactiontimes may be used if desired. Atmospheric pressure is normally used forthe reaction, although subatmospheric or superatmospheric conditionsmight be employed.

Substrate materials are readily available by procedures taught in theprior art. For example, the various chlorophenoxythioacetamides might beprepared by reacting the appropriate chlorophenoxyacetonitrile withalcoholic solution of ammonia and hydrogen sulfide (Fritzsche, Journalof Pracktische Chimie (2) 20, 279). The corresponding N-alkyl-chlorophenoxythioacetamides may be prepared by reacting thethioacetamides with an alkylamine. Alkyl iodide is availablecommercially.

The instant compounds have been found to be unexpectedly effectiveherbicides in that they are very harmful to plants normally consideredundesirable, such as rape and broadleafed weeds, while being relativelyharmless toward such plants as corn and wheat.Methyl-N-methyl-Z,4-dichlorophenoxythioacetimidate is the preferredcompound for this purpose;

it is especially useful as a precmergence herbicide and is effectiveagainst crabgrass.

Normally, the instant compounds will be used as the active ingredient inan herbicidal composition, although they might also be used without acarrier. Various diluents and carriers may be employed and the percentof active ingredient may be varied. Although compositions with less thanabout 0.5 percent by weight of active ingredient may be used, it ispreferable to use compositions containing at least about l.0 percent ofactive ingredient because otherwise the amount of carrier becomesexcessively large. Activity increases with the concentration of activeingredient, which may be I0, 50, percent or even higher.

The amount of composition which is applied for effective herbicidalaction is dependent upon considerations such as the type of undesirableplant to be killed, the density of undesirable plants, and soil andclimatic conditions. Usually, sufficient composition will be applied toprovide about 8 to 16 pounds of active ingredient per acre.

The instant herbicidal compositions may be in the form of a solution,with the solvent being selected from acetone, dichloromethane and thelike. These solutions can be applied to the plants in a direct mannersuch as by spraying, sprinkling, drenching, etc. Water suspensions canalso be applied in this manner, with dispersing and emulsifying agentssuch as sodium alkyl sulfates and sulfonates and the like.

Application can also be achieved by dusting a powder in which the activeingredient is dispersed. Suitable carriers include finely powderedmaterial such as clays, fullers earth, talc, etc.

The instant compounds may constitute the sole active ingredient in theherbicidal compositions, but they might be effectively used incombination with other active ingredients, such as other herbicides,insecticides and other plant treating agents.

The following examples are provided to more fully illustrate the instantinvention. They are provided for illustrative purposes only and are notto be construed as limiting the scope of the instant invention, which isdefined by the appended claims.

EXAMPLE I Preparation of Methyl-N-Methyl-2,4-Dichlorophenoxythioacetimidate Five grams ofN-methyl-2,4-dichlorophenoxythioacetamide, 3.6 grams of methyl iodideand a few drops of phenolphthalein were added to a ml. three-neckedflask containing 60 ml. of absolute ethanol. The flask was fitted with areflux condenser, a stirrer, and a thermometer. About 1.4 grams ofsodium methylate in 20 ml. of absolute ethanol was then added slowlywith stirring to the mixture over a period of IS minutes whilemaintaining the temperature of the mixture between 40 and 45 C. Themixture was heated at 40 to 45 C. and stirred for another 15 minutes,until about neutral, as indicated by the disappearance of the redphenolphthalein color. Water was then added to the mixture and themixture was filtered. The separated solid material was mixed with 25 ml.of methanol and the mixture was filtered. The separated solid was dried.Yield was 3.5 grams, melting between 86 to 88 C. A melting point of 88to 89 C. was obtained by recrystallizing from methanol.

The procedure of Example I is repeated wherein an equivalent amount ofappropriate chlorophenoxythioacetamide is used to afford the followingproducts:

Methyl-N-methyl-2,5-dichlorophenoxythioacetimidate EXAMPLE IllHerbicidal Activity The following crop species and weed species wereplanted in metal flats (l2 by 8.5 by 4 inches) in greenhouse pottingsoil containing one-third mixed clay and sand, one-third mushroom soil,and one-third peat moss. The pH of the soil was 6.8 to 7.2.

Crop Species Corn, Zea mays, Hybrid U.S. l3

Wheat, 'l'rilicum vulgurt'. variety Thorne Weed Species Rape CrabgrassEach flat received a volume of spray equal to 80 gallons per acre of anacetone solution of methyl-N-methyl-2,4,-dichlorophenoxythioacetimidate. The concentration of the solution wasadjusted to provide application of 16 pounds of active ingredient peracre. Immediately after spraying, the test flats were placed in aluminumtrays and were irrigated until the surface of the soil in the flat wasuniformly moist (at field capacity). Additional subirrigation wasprovided as needed to maintain moisture. No surface irrigation wasapplied.

The flats were sprayed within 1 day after seeding in preemergence tests,and 8 to 10 days after seeding in the postemergence tests. Results wereobserved 14 days after spraying.

The effect of the herbicides was evaluated in terms of the injury-ratingindex scale, ranging from O to 10 as follows:

No apparent injury l,2.3 Slight injury 4.5.6 Moderate injury 7,8,9Severe injury (plants will die) Plants were dead An injury rating of 3is the maximum tolerated for crops and a rating of? is the minimumacceptable on weed plants.

v I Injury Rating Plant Preemcrgcncc Pollemcrgence Corn 2 4 Wheat 2 4Rape 10 I0 Crabgrass 8 I claim:

1. A herbicidal composition comprising an inert carrier and aherbicidally toxic amount of an active ingredient of the formula:

wherein R is hydrogen or chlorine.

2. The herbicidal composition of claim 1 wherein R is hydrogen.

3. The herbicidal composition of claim 1 wherein said compound ismethyl-N-methyl-Z,4-dichlorophenoxythioacetimidate.

4. A method of controlling rape and crabgrass in corn and wheat whichcomprises spraying soil in which the corn and wheat are planted, priorto emergence of the corn and wheat, with a compound of the formula:

wherein R is hydrogen orchlorine, in an amount sufficient to inhibit thegrowth of the rape and crabgrass. 5. The method of claim 4 wherein R ishydrogen.

6. The metho'dof claim 4 wherein said compound is methyl-N-methyl-2,4dichlorophenoxy-thioacetimidate.

i i i UNITED STATES PATENT OFFICE 9 (56 CERTIFICATE OF CORRECTION PatentNo. 3 647 413 Dated March 7 1972 Inventor) Edmund J. Rumanowski It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1, line 40, after "of" insert a--.

Column 1, line 48: Cancel Cl s-cH CHO- -C=N-CH NaI CH OH and substitute:

S-CH c1 I 3 O--CH --C=N--CH NaI CH OH Signed and sealed this 28th day ofNovember 1972.

(SEAL) Attest: .J

EDWARD M.FLEI'CHER,JR. ROBERT GUTI'SCHALK Attesting Officer Commissionerof Patents

2. The herbicidal composition of claim 1 wherein R is hydrogen.
 3. Theherbicidal composition of claim 1 wherein said compound ismethyl-N-methyl-2,4-dichlorophenoxythioacetimidate.
 4. A method ofcontrolling rape and crabgrass in corn and wheat which comprisesspraying soil in which the corn and wheat are planted, prior toemergence of the corn and wheat, with a compound of the formula: whereinR is hydrogen or chlorine, in an amount sufficient to inhibit the growthof the rape and crabgrass.
 5. The method of claim 4 wherein R ishydrogen.
 6. The method of claim 4 wherein said compound ismethyl-N-methyl-2,4-dichlorophenoxy-thioacetimidate.